Graylog API wsdl file

Hello,
I wonder how to get WSDL file which can be used to call Graylog API via tools like SOAPUI to craft proper API calls for further use in other software?

Interactive API browser in Web interface of Graylog is somewhat useful but copy/paste and not way to save calls other way as next copy/paste each time is not ideal solution to develop software.

With Best Regards,
Jakub